If we go further back in time, mobile phones were bricks used only by business people and tech enthusiasts. They didn't have mass market appeal because the technology wasn't there yet. Once devices got to be more powerful, compact and capable, everyone wanted one and the market exploded.
I suspect the same is happening with XR. Nobody wants to strap on a giant and clunky headset. But do you really not see the mass appeal in a pair of smart sunglasses that augments computing in a way we haven't experienced before?
The technology has the potential to disrupt computing as we know it, but it's _really_ hard to get right, which is why the experimental stage has lasted for so long. XR is _much_ more complicated than any computer interface we've had so far, and requires advancements in several cutting edge tech to align: display, battery, computer vision, voice recognition, miniaturization, etc., and, of course, the price to come down.
There's a reason all these companies are pushing so hard for this. We're still a few years away from reaching the iPhone-like boom, but Apple getting into the field is a sign that this is not a fad. This first generation is obviously not a mass market product, but the tech and price will improve until it becomes one.